1. Field of the Invention
The present invention is related to the field of data communications. More specifically, the invention relates to protecting a network connection between two Ethernet devices in the network. Such connections may include, for example, a connection between a SONET network element and an Ethernet switch.
2. Description of the Related Art
Several techniques exist for protecting network connections, such as in a Local Area Network (LAN) or a Wide Area Network (WAN). Two popular protection schemes are the spanning tree protocol, which is documented in the IEEE 802.1D standard, and trunking, which is documented in the IEEE 802.3ad standard.
The spanning tree algorithm allows Ethernet devices, such as bridges and switches, in an Ethernet network to dynamically create a loop-free set of paths. Loops in an Ethernet network may result in forwarding loops, in which broadcast and multicast traffic circulates endlessly and continues to grow as new broadcast and multicast traffic is transmitted. Eventually the traffic rate gets so high that the Ethernet network is saturated. The spanning tree protocol provides network protection at the LAN level by building a complex hierarchical management structure between all Ethernet devices in the network. A special management protocol is regularly broadcast between each Ethernet device to monitor the network topology and to detect fault conditions. If one leg or section of the path is interrupted or fails, the spanning tree algorithm allows the Ethernet network to dynamically build another loop-free set of paths. However, depending on the complexity of the Ethernet network, the spanning tree algorithm may be complex to implement, and a significant amount of time may be required for network reconfiguration in the event of a failure on one of the paths.
The trunking protocol provides a means to aggregate multiple links between two Ethernet devices. While normally a loop condition occurs when parallel connections are established between Ethernet devices, trunking eliminates this loop condition by treating the parallel connections as an aggregation group or a single link. Traffic is load shared across the parallel links, and thus trunking makes for a fault tolerant connection. When one or multiple links fail, the aggregation group will converge to a new configuration. However, the bandwidth provided by the failed links is lost. Furthermore, there is no direct expansion of the standard to work with optical transport equipment, such as SONET/SDH equipment. Finally, all links in the aggregate group need to be configured in duplex mode and have the same bandwidth.
An Ethernet protection system comprises an Ethernet communication device operable to be connected to first and second Ethernet lines forming a parallel connection. The Ethernet communication device is able to select the first Ethernet line and transmit and receive data over the first Ethernet line, and upon detecting a failure in the first Ethernet line, automatically select the second Ethernet line and transmit and receive data over the second Ethernet line.
An Ethernet protection system for protecting an Ethernet connection defined by first and second Ethernet lines forming a parallel connection comprises a first Ethernet mapper card, a second Ethernet mapper card, and a switching device. The first Ethernet mapper card is operable to be connected to the first Ethernet line, and the second Ethernet mapper card is operable to be connected to the second Ethernet line. The switching device is connected to the first and second Ethernet mapper cards and a communication line, and is operable to switch a connection to the communication line between the first and second Ethernet mapper cards.